WDPN33 PGTW 281500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 11W (CO-MAY) WARNING 
NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.2N 127.4E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 47 NM NORTH-NORTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A BROAD
AND ELONGATED LOW-LEVEL CIRCULATION CENTER TRACKING NORTHWESTWARD
ALONG THE LOW-LEVEL FLOW OF A SUBTROPICAL RIDGE TO THE NORTH.
FLARING CONVECTION WITHIN THE OUTER BANDS OF THE TROPICAL
DEPRESSION (TD) 11W. AN EARLIER 280936Z WSFM MWI 89GHZ MICROWAVE
IMAGE REVEALS THE SHALLOW NATURE OF THE CIRCULATION WITH MINIMAL
CONVECTION EXCEPT ALONG THE OUTER BANDS. WATER VAPOR IMAGERY
REVEALS AN UPPER-LEVEL CYCLONE TO THE NORTHWEST ENHANCING THE
MARGINAL OUTFLOW POLEWARD. THE INITIAL POSITION AND INTENSITY ARE
PLACED WITH HIGH CONFIDENCE BASED ON A 281250Z METOP-B ASCAT IMAGE
REVEALING THE ELONGATED LLCC ON A WEST-EAST AXIS NORTH WITH A BAND
OF 20-30KTS OF WIND TO THE NORTH.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.5 - 35 KTS
   CIMSS SATCON: 37 KTS AT 280947Z
   CIMSS ADT: 28 KTS AT 281140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: WEAK POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TD 11W WILL CONTINUE TO BE DRIVEN
NORTHWESTWARD UNDER THE WEAK STEERING INFLUENCE OF THE SUBTROPICAL
RIDGE TO THE NORTH FOR THE NEXT 24 HOURS. AFTER TAU 24, THE SYSTEM
WILL CURVE NORTHWARD WHILE ROUNDING THE SOUTHWESTERN QUADRANT OF
THE RIDGE. AFTER TAU 96, THE SYSTEM WILL CURVE NORTHEASTWARD ON THE
LOW-LEVEL FLOW AS A DISSIPATED SYSTEM. TD 11W WILL REMAIN IN A
MARGINAL ENVIRONMENT FOR DEVELOPMENT FOR THE FIRST 12 HOURS OF THE
FORECAST PERIOD DUE TO MODERATE VERTICAL WIND SHEAR AND DRY AIR
ENTRAINMENT FROM THE UPPER-LEVEL CYCLONE TO THE NORTHWEST. VERTICAL
WIND SHEAR WILL DECREASE FAVORABLY AFTER TAU 24, ALLOWING FOR
GRADUAL REINTENSIFICATION AS THE CYCLONE DRIFTS WESTWARD AND
BECOMES WEAK. THE SYSTEM WILL CONTINUE TO INTENSIFY UNDER A
MARGINALLY FAVORABLE ENVIRONMENT TO A PEAK OF 40KTS BY TAU 48. THE
SYSTEM WILL MAKE LANDFALL BETWEEN TAU 48-72, INITIATING A
DISSIPATION DUE TO TOPOGRAPHIC INTERACTION. AFTER TAU 96, THE
SYSTEM WILL PASS INTO THE YELLOW SEA, BUT STRONG VERTICAL WIND
SHEAR AND AN UPPER-LEVEL TROUGH ALOFT WILL INHIBIT REDEVELOPMENT.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT TD 11W WILL TRACK NORTHWESTWARD THROUGH TAU 12, BEFORE CURVING
NORTH-NORTHWESTWARD THROUGH THE END OF THE FORECAST. THE
CROSS-TRACK SPREAD BY TAU 120 IS 300NM DUE TO VARYING
INTERPRETATIONS OF THE STRENGTH OF THE RIDGE TO THE NORTH AND RATES
OF DISSIPATION.  THE INTENSITY GUIDANCE IS IN
GENERAL AGREEMENT THAT THE SYSTEM WILL REACH A PEAK INTENSITY
BETWEEN 35-40KTS BETWEEN TAU 36-48, BUT MAY REACH HIGHER
INTENSITIES IF THE SYSTEM WERE TO REMAIN OFFSHORE FOR LONGER THAN
FORECASTED.


FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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